This invention relates to a data recording device for a motion picture film for recording the digital speech information on a motion picture film in the form of dots.
In the motion picture film in general, frame-shaped picture recording areas are provided at a mid portion, and two rows of film take-up perforations are formed on both sides of the picture recording areas. An analog sound track is formed is formed along a straight line between the picture recording areas and one of the rows of perforations. It is on this analog sound track that audio signals are recorded in an analog form.
Recently, with the progress in the digital techniques, attempts are being made for digitally recording the audio information. Since the recording positions for the picture recording regions and the analog sound tracks are standardized by the Society of Motion Picture and Television Engineers (SMPT), an association of motion picture and television engineers in U.S.A., the digitized audio information (audio data) are recorded in positions other than the recording positions for the picture recording regions or the analog sound track.
Up to now, a redundant area between the right-hand side perforations and the right-hand side edge of the motion picture film was allocated for a digital sound track for the right channel, and a redundant area between the left-hand side perforations and the left-hand side edge of the motion picture film was allocated for a digital sound track for the left channel. The audio data was recorded along a straight path on each of the digital sound tracks along the film running direction.
Specifically, a light shutter type data recording apparatus has been known as a device for recording the audio data.
The light shutter data recording device has a photo-electric device, such as a so-called PLZT plate, having plural shutter portions arrayed in a staggered configuration. A laser beam is radiated from the rear side of the PLZT plate, and the opening/closure of the respective shutter portions of the PLZT plate is controlled responsive to the audio data. Thus the laser beam is transmitted through the PLZT plate via the opened shutter portions.
Since the respective shutter portions of the PLZT plate are opened and closed responsive to the audio data, the laser beam transmitted through the PLZT plate carries the information corresponding to the electrical audio data and is radiated as audio data converted into light (audio data carrying light).
The audio data carrying light, radiated from the PLZT plate, is converged by a recording lens so as to be illuminated on the digital sound tracks on the motion picture film.
This sensitizes the motion picture film in dependence upon the audio data carrying light, so that the audio data is recorded thereon in the form of dots.
The data recording device for a motion picture film may also be designed to have a head unit including an array of light emitting diodes (LEDs) corresponding to a data pattern.
With such data recording device, the light emitting diodes are turned on in dependence upon the audio data. This translates the electrical audio data into the audio data carrying light which is illuminated via a recording lens on the digital sound tracks of the motion picture film. Thus the motion picture film is sensitized in dependence upon the audio data carrying light for recording the audio data thereon in the form of dots.
With the above-described light shutter data recording apparatus, employing the photo-electric device, such as the PLZT plate, the shutter portions could not but be arranged in a staggered configuration for constructional reasons, such as due to the electrode array of the photo-electric devices. Thus the audio data are recorded in a staggered configuration on the motion picture film, while they cannot be recorded on a straight path, so that only a small quantity of audio data can be recorded on the motion picture film.
On the other hand, with the data recording device for the motion picture film having the LED array as the head unit, the audio data can be recorded linearly, because the LEDs can be arrayed linearly. However, if one-line audio data, for example, is recorded by 80 dots, it is necessary to array 80 LEDs with a narrow gap between the neighboring LEDs.
The current required to turn on a LED is e.g., 20 mA, so that the current of 1.6 A is required to turn on the 80 LEDS. Thus a large quantity of heat is evolved during the time of turning on of the LEDs, thus reducing the life of the LEDs under the effect of heat. In addition, a heat sink for heat dissipation is required, thus raising the problem in durability and cost.